Various kinds of headlights and the like are used for automobiles, and a polycarbonate resin, which is lightweight, unbreakable, and has excellent translucency, is used as a material for a lens body that is a surface for transmitting light emitted by an illuminant. Since the polycarbonate resin is degraded or turned yellow by ultraviolet rays, in the case of new vehicles, a surface layer of reinforced plastic or a surface layer of a resin containing an ultraviolet ray absorbent (hereinafter simply referred to as “a surface layer of reinforced plastic or the like”) is provided to prevent the lens body from degrading or yellowing (see, for example, Patent Document 1).
However, after multiple years of use, automobiles have a problem of age deterioration wherein the surface layer of reinforced plastic or the like is partially exfoliated and the surface of the lens body ages and turns yellow because the surface of the bare lens body is exposed to ultraviolet rays or acid rain or hit by flying gravel flipped up by wheels. In addition, since the surface of the lens body of the headlights or the like which was degraded and turned yellow, lacks translucency, transparency, and luster, decreasing brightness of the headlight or the like and impairing of an aesthetic appearance have been problems.